Process of making soluble phosphates.



F. J.l MAGHALSKB.

PRooEss or MAKING soLUBLE PHosPHATEs,

APPLICATION FILED NOV. 6, 1907.

@02,4259 Patented 001:. 27, 190s.'

UNTED STATES 'PATENT FFUE,

FLORENTINE J. MACHALSKE, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO AMERICAN REDUCTION r COMPANY, OF PITTSBURG, y. PENNSYLVANIA.

PROCESS OF MAKING SOLUBLE 'PHOSPHATES y Application led November 'Specification of Letters Patent.

Patented Oct. 27', 1908.

s, 1907. serial 110.400,947.

To all whom it may concern'.

lBe it known that I, FLORENTINE J. MACHALSKE, a' citizen of the United States, residing at Niagara Falls, in the county of Niagara and State of NewYork, have invented certain new and useful Improvements in Methodsy of Preparing Soluble Phospliates, of which the following is a speciication:

This invention relates to the production of soluble phosphates, and -the object of the invention is to effect their production in a higher state of purity and in a more eflicient and economical manner than has heretoforel been possible.

According to methods heretofore used for the production of superphosphates, a phosphate rock or other material containing tricalcium phosphate is mixed With sulfuric lacid in proportion tofyield either dicalcium phosphateor mono-calcium hosphate or a mixture of these, as expresse by the following equations:

1) cano, raso4 caso;4 caznzaosj 2) cargo, naso4 2caso4+ carnaos.

.In either case the sulfuric acid used appears in the product as calcium sulfate and is doubly disadvantageous as unnecessarily diluting the soluble phosphate, and as giving rise under certain conditions to the effect known as reversiom whereby the soluble hosphate reverts to a less soluble or insolule form.

According to my invention a phosphate' rock or other source of phosphoric acid is subjected to the action of sulfur dioxid in the presence of a limited proportion of water, or of sulfurous acid, under such conditions that the hosphoric acid is rendered soluble and calcium sulte is formed. The reaction may occur With'or Without the application of heat or pressure and is exempliied by the following equation: v

3) CfaPZO8 2,802 211,0 I Cal-1,1320, CaSQ? The'soluble phosphate is dissolved in a suitable solvent, as water containing sulfur dioxidgthereby separating it from a residue consisting in part or entirely of calcium suliite. The calcium suliite may then' be burned or calcined for the production of sulfur dioxid for the continuance of the process as per equation:

(4) CaS()3 heat Ca() SO2.

The mechanical losses of sulfur dioxid incident to the process may be supplied by burning sulfur or other source of sulfur dioxid with the sulfite, or by the introduction of sulfur dioxid derived from any suitable source., i

The dissolved phosphate may beseparated out by concentration methods or otherwise utilized. It may be conveniently converted into sodiurn phosphate by reaction with sodium sulfate according to the equation:

5; Gammo, +Nt2so4 zNaHzrd (aso4 separated from the insoluble calcium sulfate. Or by treatment With calcium hydroxid it may be converted into di-calcium phosphate as per equation:

6) marzo, Loncin2 banano, 211,0.

may be4 avoided.

The method may be carried out in any de` sired type of' apparatus, one form of which is illustrated in the accompanying drawing wherein the iigure is a central vertical section.

Referring to the drawing, 1 represents a cylindricalvessel having a conical bottom 2 with a valved central discharge aperturefor the liquid contents. lVithin the'vessel is a transverse perforated plate 4 supporting a filter 5, above and upon which the phosphate the soluble sodium phosphate being readily for solution the 4necessity of concentration rock is disposed. 6 represents a perforated pipe for the admission of live steam to the interior of the vessel, and 7 a closed steam coil. 8, 9 are apertures provided with suitable closures and serving respectively for charging the phosphate rock and removing the undissolved residue.

In operation the moist ground rock or sludge 1s charged into the vessel through the aperture 8, the apertures closed, and sulfur dioxid is forced into the vessel through pipe 10 by means of a pump until a pressure of -60 pounds per square inch is reached. Thereafter it is permitted to react for a suitable period, as an hour or more, when hot or cold Water, preferably the former, is turned into the vessel and distributed over and through the charge by means of a spray nozzle. l1. The pressure within the vessel will quickly disappear owing to the absorption of the gas by the water', whereupon the liquid contents of the vessel, comprising a strong solution of calcium phosphate oontaining a small proportion of calcium suliite, are discharged into a suitable tank 12 through the filter, and such calcium sulfite as may accompany the liquid is permitted to settle out. The clear liquid cont-aining the soluble phosphate may then be drawn into another vessel, 13, and mixed therein with tankage or the like or utilized for the preparation of a fertilizer of any'desired composition.

lf the phosphate rock in the vessel or digester, after the usual leaching, is shown. by

. test to retain considerable proportions of phosphoric acid the operation may be repeated. When the extraction of the phosphoric acid is commercially complete the residue, consisting largely of calcium sulfite, is removed from the vessel, dried, and burned for the production of sulfur dioxid which is utilized in the repetition of the process.

l. claim: 1. The method of making soluble phosphates which consists in reacting with sulfur dioxid gasin the presence of a limited under conditions yielding a soluble phosphate and calcium sulite, and leaching out the phosphate by a suitable solvent, thereby obtaining a strong solution of calcium phosphate containing a smallproportion of calcium ,sulfite 2. The method of making soluble phosphates which consists in reacting with sulfur dioxid gas in the presence of a limited proportion of water upon tri-calcium phosphate under conditions yielding a soluble phosphate and calcium suh'ite., and leaching out the phosphate bya dilute solution of sulfur dioxid, thereby obtaining a strong solution of calcium phosphate containing a small proportion of calcium sulfite.

phosphates which consists in reacting with sulfur dioxid gas on moistened tri-calcium' phosphate, leaching out with a dilute solution of sulfur dioxid the soluble phosphate produced, thereby obtaining a strong solution of calcium phosphate containing a small proportion of calcium suliite decomposing the residual calcium suliite to produce sulfur dioxid, and utilizing said sulfur dioxid in the continuation of the process.

ln testimony whereof, l affix my signature i in presence of two witnesses.

FI ORENTI N E J. MACHALSKE. \Vitnesses: l HENRY KIRKLAND,

JAMES BAKER.

roportion of water upon tri-calcium phosplliate 3. The cyclical method of making soluble 

